1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
It is considered that a semiconductor device with low power consumption is more and more important for long battery life or for eco-friendly goods. In order to manufacture such a semiconductor device with low power consumption, a semiconductor device has been miniaturized. However, as a demerit of miniaturization of a semiconductor device, degradation of electrical characteristics of a semiconductor device, especially an increase in leakage current, is obvious (Patent Document 1).
In order to reduce a leakage current, in a semiconductor device including silicon as a semiconductor layer, specifically, a field-effect transistor, a junction depth of a source region and a drain region that are adjacent to a channel region of the transistor is made to be shallow. However, the method is not sufficient for reducing a leakage current.